Method of electromagnetic stirring in continuous metal casting process

Abstract

A method of electromagnetically stirring molten metal in an unsolidified portion of a continuously cast strand by a magnetic field formed by applying alternating current to at least two exciting coils, the method comprising: supplying to one of the exciting coils a first alternating current of a frequency in the range of 1-60 Hz and to the other one of the exciting coils a second alternating current with a frequency difference in the range of 0.03-0.25 Hz from the first alternating current to form a varying composite magnetic field thereby to induce stirred movement of varying direction and intensity in the molten metal.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A method of electromagnetically stirring molten metal in an unsolidified portion of a continuously cast strand by a magnetic field formed by applying alternating current to at least one group of exciting coils comprising at least two exciting coils, wherein said method comprises: supplying to one of said exciting coils in each group a first alternating current of a frequency in the range of 1-60 Hz and to the other one of said exciting coils in each group a second alternating current with a frequency different in the range of 0.03-0.25 Hz from said first alternating current to form a varying composite magnetic field thereby to induce stirred movement of varying direction and intensity in said molten metal.   
     
     
       2. The method as set forth in claim 1, wherein said one of said exciting coils in each group is supplied with a first alternating current of a frequency in the range of 1-20 Hz while the other one of said exciting coils in each group is supplied with a second alternating current with a frequency difference of 0.04-0.20 Hz from said first alternating current. 
     
     
       3. The method as set forth in claim 1, wherein said one of said exciting coils in each group is supplied with a first alternating current of a frequency in the range of 50-60 Hz while the other one of said exciting coils in each group is supplied with a second alternating current with a frequency difference in the range of 0.06-0.2 Hz from said first alternating current. 
     
     
       4. The method as set forth in claim 1, wherein said composite magnetic field has a maximum flux density in the range of 100-2300 gauss at the surface of said continuously cast strand.